Wolves, Winters, Climate Possible Factors in Moose Decline

DNR Press Release:
Photo: Michigan DNR Photo: Michigan DNR
The Michigan Department of Natural Resources today announced the results of its 2015 moose population survey in the western moose range of the Upper Peninsula, an important tool in managing the species.
The 2015 population estimate in the western U.P. is 323, compared to an estimate of 451 in 2013. From 1997 to 2007, surveys of prime moose habitat in Baraga, Iron and Marquette counties suggested the U.P.’s moose population was growing at a modest rate of about 10 percent per year. From 2009 to 2013, survey results showed an apparent change in that trend, with the growth rate slowing to about 2 percent per year.
“There is inherent uncertainty with any population survey, and due to the fact that the 2013 and 2015 estimates have some overlap in confidence intervals, the potential remains that the state’s moose population has remained steady rather than declining,” said Chad Stewart, deer, elk and moose management specialist for the DNR. “However, coupled with survey records that show a decrease in the number of moose calves seen with cows this year, it’s quite possible that we’re looking at a considerable drop in numbers.”
Future surveys will be needed to identify any long-term trend for Michigan’s moose population. Other states and provinces have reported declines in moose populations near the southern edge of North America’s moose range, yet other populations are holding steady or increasing. Researchers in Michigan have hypothesized several potential causes for a possible decline of moose numbers in Michigan. Among potential factors:
  • Back-to-back severe winter weather that negatively affected moose condition, survival and reproductive success.
  • Year-round climatic changes, especially warmer temperatures, that led to increased parasite loads on moose, weakening their overall condition.
  • A possible increase in wolf predation on moose calves due to the region’s lowered deer population.
The moose range in the western Upper Peninsula covers about 1,400 square miles. Every other year, DNR staff members survey most of that area from the air. In 2015, the flights covered all survey plots within the core moose area – where 80 to 90 percent of the western U.P. moose population is located – along with a sampling of the non-core plots as well.
The survey is completed by flying transects over prime moose habitat to count moose seen from the air. The number counted is then extrapolated by a computerized population modeling program to attain the final estimate. The next moose population survey is planned for early 2017. However, given moose population trends, the DNR will again recommend to the Michigan Natural Resources Commission that there be no moose hunt in the state.
For more information about moose in Michigan, visit www.michigan.gov/moose.

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